<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>

</body>
<script>
    var week = prompt('请输入星期几')
    if (week == 1) {
        alert('今天是星期一')
    } else if (week == 2) {
        alert('今天是星期二')
    } else if (week == 3) {
        alert('今天是星期三')
    } else if (week == 4) {
        alert('今天是星期四')
    } else if (week == 5) {
        alert('今天是星期五')
    } else if (week == 6) {
        alert('今天是星期六')
    } else if (week == 7) {
        alert('今天是星期日')
    }
</script>

</html>